Inflammatory bowel diseases (IBD) that are associate with a dramatic increase in colorectal cancer occur throughout the world with an annual incidence of approximately 12/100,000 people. Aberrant activation of neutrophils and a profound increase in lipid and peptide mediators are cardinal signs of these inflammatory diseases as well as for ischemia reperfusion injury, a known complication of surgical procedures. How acute inflammatory responses switch from vital host defense to aberrant inflammation and neutrophil mediated tissue injury remains to be completely elucidated. Therefore, endogenous mechanisms that disrupt pro-inflammatory circuits are of interest. Aspirin and omega-3 polyunsaturated fatty acids (PUFA) are therapeutic agents that demonstrate benefits in inflammatory diseases as well as prevention of colon cancer. However, their mechanisms of action still needs to be clearly defined but targets the formation of lipid mediators namely eicosanoids. Both therapeutic agents trigger the formation of novel classes of anti-inflammatory lipids, namely 15R-lipoxins and omega-3 PUFA derived 15R-and 18R-series eicosanoids. This study shall test the hypothesis that acute inflammation induces a regulated and temporal generation of anti-inflammatory lipid signals and that omega-3 fatty acid and aspirin augment these protective lipid mediator circuits. The specific aims of this application will employ a combined approach of structural elucidation, molecular biology and transgenics to delineate three main aspect of the role of lipid signals in neutrophil mediated intestinal injury: i) Establish the temporal relationship of pro- and anti-inflammatory eicosanoids. ii) Determine the impact of aspirin and omega-3 PUFA on eicosanoid profiles and elucidate novel protective lipid mediators. iii) Determine if novel aspirin and omega-3 PUFA triggered lipid mediators are protective against aberrant PMN activation and if changes in expression of receptors for lipid mediators are markers for aberrant intestinal inflammation. The broad and long-term objectives of this application are to elucidate endogenous pathways that block PMN mediated injury to promote resolution of inflammation. Results from this project may provide novel anti-inflammatory tools for controlling inflammatory diseases such as Ulcerative Colitis and Chron's Disease.